Aircraft instruments are commonly mounted upon the instrument panel within a holder or clamp utilizing a mechanical linkage, cam, or the like for constricting the instrument within the clamp. The clamp is supported on the backside of the instrument panel, and through operating means accessible from the panel front the clamp may be tightened upon the instrument casing after the instrument has been inserted through the panel opening into the clamp. By operation of the clamp actuator the instrument may be readily inserted into the clamp, and removed therefrom, through the front side of the panel.
An instrument clamp has been proposed using a compressible elastomer wherein expansion of the elastomer is utilized to produce a frictional support of the instrument casing, and such a construction is shown in U.S. Pat. No. 3,599,910. This patent utilizes an elastomeric ring and translatable collars for compressing the ring whereby a circumferential engagement with the instrument casing is produced. However, as the elastomer support is not throughout the length of the holder the instrument casing is capable of angular movement with respect to the holder, and a positive and vibration absorping support of the instrument is not achieved.
It is an object of the invention to provide an instrument clamp which may be molded of a dielectric material by high production techniques wherein superior dimensional tolerances may be achieved as compared with conventional metal stamped clamps.
An additional object of the invention is to provide an instrument clamp holder which is of a greater rigidity than conventional clamp constructions and reduces the likelihood of the instrument casing binding in the clamp during removal thereof.
A further object of the invention is to provide a clamp for instrument casings wherein an elastomer is used to hold the casing within the clamp producing a high friction mounting having significant shock and vibration isolation characteristics.
Additionally, an object of the invention is to provide an instrument casing clamp which readily releases the instrument casing when desired, and wherein the actuation screws for the clamp will not loosen during vibration.
Another object of the invention is to provide an instrument clamp for aircraft panels capable of meeting standard clamp specifications, and wherein operation of the clamp is readily achieved from the panel front by screw actuators, such screw actuators also mounting the clamp upon the panel.
In the practice of the invention a clamp of generally rectangular annular configuration is injection molded of a nonmetallic dielectric synthetic material and the housing defines an opening having four corners each having an elongated recess defined therein by the adjacent housing sides. An elongated elastomeric element is mounted within each recess, and each element includes a bore extending the length thereof in which a threaded screw is received. The head of the screw is adapted to be disposed adjacent the instrument panel at the front side thereof, and a compression plate is mounted upon the opposite screw end in engagement with the elastomer material wherein rotation of the screw compresses the elastomer and forces the elastomeric material radially inward for engagement with the instrument casing closely received within the housing opening. Thus, the instrument casing is frictionally supported within the clamp housing at four equally spaced locations substantially throughout the clamp length and upon the elastomeric material. In this manner the instrument casing is isolated from the clamp and instrument panel by the elastomeric material, and also electrically isolated therefrom.
As the screw heads are accessible from the front of the panel front the compression of the elastomeric elements is readily achieved, and the instrument casing may be easily inserted into, or removed from the clamp.